The invention relates to a cooled slider plate, particularly a water-cooled hot air slider plate, according to the preamble of claims 1, 7, 9 or 11.
Slider plates according to DE-C 23 66 032 are in general use. These serve to block off pipes carrying hot gas which can have a diameter of up to approximately two meters and more.
A known slider plate of this type usually incorporates a seal stretching along its perimeter and this seal delimits a part of the slider plate lying radially inside. According to DE-C 23 66 032 this part of the slider plate is cooled with the aid of a cooling medium. Since, when the slider plate is closed, temperatures of over 1000xc2x0 C. can fall over the slider plate, separate cooling is necessary, in order to reduce heat-dependent stress and a consequent bending of the slider plate.
In concrete terms, in the known construction, the part of the slider plate delimited by the seal includes two plates, which are axially distanced from one another by dividing walls designed as spiral shaped. A continuous flow channel is formed by these dividing walls, from a cooling medium inlet, situated on the peripheral edge of the slider plate, to an outlet, likewise arranged on the peripheral edge, the cooling medium being guided inwards at first in a spiral shape, in order to flow from there, i.e. from a flow reversal point situated in the central area of the slider plate, outwards to the cooling medium outlet, again flowing in a spiral shape.
A disadvantage of this known construction is the expensive manufacture of the slider plate. For example, it is only possible with relatively large expenditure to weld the dividing walls delimiting the double spiral shaped cooling channel, with the two plates. In addition to this, in the known design, a large amount of cooling medium is required in order to achieve adequate cooling of the slider plate. The necessary pump capacity is correspondingly high. Moreover, in this known design, an unnecessarily large amount of heat is lost from the process. Different cooling between slider plate and seal seat has a particularly disadvantageous effect, as, through this, additional stress is produced, which can reduce both the reliability and life of the slider plate.
From DE-A 22 43 588 a slider plate according to the preamble of claim 1 is known, which in comparison with the state of the art according to DE-C 23 66 032 is considerably simpler in construction. On the other hand, the area covered by the cooling medium is relatively small, thus the slider plate according to DE-A 22 43 588 cannot be used for blocking purposes at high temperatures, or only in a limited way.
It is the purpose of the present invention to develop the cooled slider plate just mentioned, in such a way that it can be used for blocking purposes at high temperatures yet remain simple and inexpensive to manufacture.
This purpose is fulfilled alternatively through the features of the characterising parts of the independent claim.
The slider plate according to the invention can be manufactured simply and inexpensively, since just a simple pipe has to be bent into a double spiral shape. Furthermore, through the choice of a particular inner diameter or a particular wall thickness, individual cooling or stability needs of the slider plate can be taken into account.
According to the invention, the neighboring sections of the pipe bent in a spiral shape adjoin one another, with the exception of a central pipe part forming the flow reversal area, thus an equally spiral-shaped line of contact is formed. In the region of the line of contact, the adjoining pipe sections are preferably connected with one another and thus a plate element of particularly stable shape is created. For making the connection, welding is particularly suitable which can be carried out simply on easily accessible parts of the line of contact.
The flow reversal occursxe2x80x94as already indicatedxe2x80x94in the central plate area through a pipe section, bent in an S-shape, which is designed as one piece with the pipe bent in a double spiral shape and creates a fluid connection between the two pipe parts designed as a spiral shape.
The central flow reversal area has, between the pipe section, bent in an S-shape, and the ajoining spiral pipe sections, a space that is not cooled by the cooling medium flowing in the pipe. For cooling this space, metal sheets are preferably arranged, axially distanced from one another, in the area of the two outer surfaces in such a way that they, together with the adjoining spiral pipe sections, enclose this space. The cooling medium can then be led from the pipe in and out of this space via inlet and outlet openings in the pipe section, bent in an S-shape.
In particular, it is possible to divide the space delimited by the two metal sheets with an intermediate plate, thus partial spaces are created, through each of which cooling medium is forced.
To improve the flow through the space enclosed by the metal sheets, it is possible for the passage of the pipe bent in an S-shape to be restricted or completely interrupted between inlet and outlet apertures. Alternatively, a piece can be taken out of the pipe bent in an S-shape.
According to the second alternative of a cooled slider plate according to the invention, the double spiral shaped cooling channel is formed in that a double spiral shaped groove, formed in a base plate, is closed with a cover plate. The flow reversal occurs again in the central area of the slider plate, the bend radius of the S-shaped groove section not being, in the manufacturing process, limited depending on the material as with the pipe. For the supply and removal of the cooling medium, the axially closed groove must, in each case, be connected at the end side with a cooling agent inlet or outlet. This alternative also offers an inexpensive way of manufacturing simply a cooled slider plate with the desired flow passage surface.
A particularly simple and quick way of applying the cover plate to the base plate is provided by xe2x80x9cexplodingxe2x80x9d same.
In a third alternative, the cooling channel is formed between a carrying plate and a sheet of metal, which form the part of the slider plate surrounded by the seal. The metal sheet has a double spiral or double meander shaped distortion, forming a corresponding channel. The distortion formed in the metal sheet can be shaped before (e.g. by impressing), during (e.g. by explosive forming) or after (e.g. by hydraulic inflation) application of the metal sheet to the carrying plate. Since sheet metal is particularly easy to shape and work, the above-mentioned possibility represents a particularly cheap manufacturing alternative for a cooling channel in or on a slider plate, the dimensions of the cooling channel being determinable by the choice of the measurements of the opening.
The metal sheet is, by preference, xe2x80x9cexplodedxe2x80x9d on to the carrying plate (explosive forming with surface contact) or connected impermeably with it by roll welding (with line contact). With both these processes, quick and secure connection of the two parts to be connected is achieved with the formation of a cooling channel which is impermeable towards the outside.
A particularly simple alternative of a cooled slider plate has bores provided in a core plate, which intersect, forming a preferably meander shaped cooling channel, which bores are in a fluid connection with one another.
To form a desired flow course, closure stoppers can be placed in the bores. A particularly simply way of doing this is offered by axial bores, provided in the core plate, which are arranged in the region of the bores to be closed and into which the closure stoppers can be inserted. On their outer side, the bores forming the cooling channelxe2x80x94apart from a cooling medium inlet or outletxe2x80x94are sealed by plugs or similar blocking members. The seal surrounding the slider plate at its perimeter, especially welded on, can be used for the radial closure of the bores.
A slider plate shaped according to the fourth alternative can also be manufactured cheaply and simply, the choice of the grid configuration and the bore diameter being able to be matched to the necessary cooling requirements for the particular plate.
For minimal cooling with a low cooling capacity, the insulation of the slider plate must be as good as possible. It is proposed, therefore, that the heat-insulating covering should be formed on both sides as well as on the perimeter, in each case in two layers, namely an inner, especially xe2x80x9cMikrothexe2x80x9d (trademark) insulation (microporous ceramic mat or plate with a thermal conductivity coefficient lambda=0.02 W/mK at 20xc2x0 C.) and an outer insulation consisting especially of a ceramic fibre foam or refractory concrete plate.
Since bending of the slider plate and/or thermal stress cannot be completely excluded despite the cooling, the outer insulation is preferably arranged with radial and axial play, thus it has sufficient play if the plate bends or expands and cannot be damaged by forces working on it. Damage of this kind is in any case to be avoided, since, if the outer insulation is broken, the hot gases come directly into contact with the inner insulation or with the central and cooled part of the slider plate. Because of this the inner insulation could, for one thing, be damaged (e.g. through the insulation melting away or on) or the cooling of the slider plate could no longer be adequate.
The insulation or insulations are preferably held by retaining bolts or pins, especially welded on ones, arranged like a grid on the slider plate.
In order to ensure the radial and axial mobility of the outer insulation, the retaining bolts or pins can be provided with a coating, which at high temperaturesxe2x80x94when it is first used, thereforexe2x80x94burns away, so that an expansion gap then occurs between insulation and bolts or pins.
An alternative possibility for fixing the outer insulation consists in providing existing tightening members, particularly tightening cords, made out of insulating material, particularly ceramic material, which are arranged in the outer insulation and guided via rings or eyelets, so that the insulation is pretensioned radially and/or tangentially. The tightening members are, by preference, embedded in the manner of a grill in the interior of the outer insulation and extend in two directions perpendicular to one another, particularly net-like or respectively in a meander shape. Play for the outer insulation in axial and radial direction can thus be guaranteed, without heat bridges arising between the surroundings and the cooled part of the slider plate.
According to a further advantageous embodiment of the invention, a tightening cord is provided inside an insulating ring extending over the outer perimeter of the slider plate and this cord consists likewise of insulating material, especially ceramic material and is tightened via ring or xe2x80x98yxe2x80x99 armatures arranged approximately at the same angular distance from one another, so that the outer insulation is held together radially.